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    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
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    <script>
      function fn() {
        console.log("hello", this);
      }
      const arr = ["a", "b"];
      arr.push("c");
      arr.push(fn);

      console.log(arr);
      arr[3](); //执行函数，this等于点（中括号）前面的对象
    </script>
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